The proportion of Americans in their prime working years who have jobs is smaller than it has been at any time in the 23 years before the recession, according to federal statistics, reflecting the profound and lasting effects that the downturn has had on the nation’s economic prospects.

By this measure, the jobs situation has improved little in recent years. The percentage of workers between the ages of 25 and 54 who have jobs now stands at 75.7 percent, just a percentage point over what it was at the downturn’s worst, according to federal statistics.

Before the recession the proportion hovered at 80 percent.

While the unemployment rate may be the most closely watched gauge of the economy in the presidential campaign, this measure of prime-age workers captures more of the ongoing turbulence in the job market. It reflects “missing workers” who have stopped looking for work and aren’t included in the unemployment rate.

During their prime years, Americans are supposed to be building careers and wealth to prepare for their retirement. Instead, as the indicator reveals, huge numbers are on the sidelines.